Gold aryl mercaptides



United States Patent 3,268,568 GQLD ARYL MERCAPTIDES Howard M. Fitch,Summit, N.J., assignor to Engelhard industries, line, Newark, N..l., acorporation of Delaware N0 Drawing. Original application Apr. 9, 1962,Ser. No. 185,819. Divided and this application July 14, 1965, Ser. No.472,026

4 Claims. (Cl. 260-430) This invention relates to novel gold arylmercaptides suitable for use in gold decorating compositions, and is adivisional application of US. application Serial No. 185,819 filed April9, 1962.

Gold decorating compositions containing gold sulforesinates are known tothe art and have been described, for example, by Boudnikoff, Compt.rend. 196. 1898 (1933), and by Chemnitius, J. Prakt. Chem. 117, 245(1927). The gold sulfo-resinates are prepared by reacting a gold saltwith a sulfurized terpene such as sulfurized Venetian turpentine. Theyare dissolved in vehicles such as oils of lavender, rosemary, .aniseed,sassafras, wintergreen and fennel, turpentine, various terpenes,nitrobenzene, amyl acetate and the like, and mixed with gold fluxes suchas salts and resinates of rhodium, chromium, bismuth, lead, cadmium,tin, copper, cobalt, antimony and uranium, Assyrian asphalt and variousrosins to form gold decorating compositions. More recently, it has beenproposed in US. Patent No. 2,490,399 to use gold cyclic terpenemercaptides in place of gold sulforesinate in such compositions. Thestructures of these gold cyclic terpene mercaptides have never beenelucidated, and the location Of the mercaptide group in the molecule isnot known. The gold mercaptide of thioborneol has been prepared byNakatsuchi, J. Soc. Chem. Ind., lap. 38, Suppl. 617B (1935), althoughthe use of this material in gold decorating compositions has not beendescribed.

Gold decorating compositions are compositions that form a film ofmetallic gold when applied to various surfaces and heated. Suchcompositions, which have been known for a hundred years or more, havebeen based on a cyclic terpene technology. The gold compounds in suchcompositions have been derivatives of cyclic terpenes and sulfur,originally in the form of sulforesinates and more recently in the formof cyclic terpene mercaptides. It has been assumed that the cyclicterpene radical is somehow essential to gold compounds suitable for usein gold decorating compositions, and other organic gold compounds havenot been employed. The gold compounds derived from cyclic terpenes havethe disadvantage of requiring relatively high firing temperatures,limiting their use to refractory substrates such as glass, ceramics,quartz and the like. They have the further disadvantage of being derivedfrom natural products that are in variable supply and of variablecomposition.

In accordance with the teachings of the aforementioned US. applicationSerial No. 185,819, useful gold decorating compositions are preparedfrom a gold aryl mercaptide and a vehicle therefor. More specifically,the gold aryl mercaptide is one having the formula Ar-S-Au wherein Ar isan aryl radical and the mercapto sulfur is attached directly to anaromatic ring of the aryl radical. Aryl radicals which can be present asthe Ar of the foregoing formula for the gold aryl mercaptides of thisinvention include mononuclear and polynuclear radicals. Exemplary ofsuch aryl radicals are phenyl, tolyl, xylyl, naphthyl, anthryl,phenanthryl, halogenophenyl, aminophenyl and carboxyphenyl.

The present invention is concerned with a particularly preferred classof novel gold aryl mercaptides in which at least one alkyl groupcontaining at least three carbon atoms and preferably from about 412carbon atoms, is

See

directly attached to an aromatic ring of the aryl nucleus. Thenuclear-substituted gold aryl mercaptides including at least one alkylgroup containing at least three carbon atoms directly attached to thearyl nucleus are particularly useful as constituents of gold decoratingcompositions because of their very remarkable and unexpected solubilityin organic solvents. Generally speaking, gold aryl mercaptides of lowsolubility in organic solvents are suitable only for use in burnish golddecorating compositions. Gold aryl mercaptides of high solubility inorganic solvents are useful not only in burnish gold decoratingcompositions but also in bright gold decorating compositions, which givegold films that require no burnishing operation and are hence muchcheaper to produce. As an example of the extraordinary effect of suchnuclear alkyl substituents on solubility in organic solvents, thesolubility of gold p-tert.-butylphenyl mercaptide in chloroform at roomtemperature exceeds 30 percent by weight, whereas the solubility of goldphenyl mercaptide under the same conditions is only about 0.0062 percentby weight. Similarly, the solubility of goldo-methyl-p-tert.-butylphenyl mercaptide in toluene at room temperatureexceeds 40 percent by weight, whereas the solubility of goldo-methylphenyl mercaptide under the same conditions is only about 0.01.3percent by weight. Similar solubility increases of a thousand-fold ormore are obtained with other nuclear ialkyl substituents containingthree or more carbon atoms and in other organic solvents. Examples ofthe preferred nuclearsubstituted gold aryl mercaptides having at leastone alkyl group containing at least three carbon atoms directly attachedto the aryl nucleus include gold p-isopropylphenyl mercaptide, goldp-tert.-butylphenyl mercaptide, gold o-methyl-p-tert.-butylphenylmercaptide, gold p-nonylphenyl mercaptide, gold p-dodecylphenylmercaptide, gold p-octadecylphenyl mercaptide, gold2,4-diisopropylphenyl mercaptide and gold 2,4-ditert.-butylphenylmercaptide.

An outstanding advantage of the gold decorating compositions containingthe novel compounds of this invention is their requiring only relativelylow temperatures to form a metallic film, which is due to the presenceof the gold aryl mercaptides. By reason of requiring only relatively lowtemperatures for forming the metallic films, some of these decoratingcompositions are well suited for decorating non-refractory materialsincluding a wide range of plastics, plastic laminates, Wood, paper,textiles, leather and the like which would be damaged by the use of hightemperatures. The gold decorating compositions previously used requiredrelatively high temperatures, due to the gold compounds present therein,to form a metallic film, and hence their application was limited todecoration of relatively refractory materials such as glass, ceramics,metals, quartz, carbon, mica, and other materials that were not damagedby the high temperatures required. The gold decorating compositionemploying the gold com pounds of this invention can be applied to theserelatively refractory materials and some can be applied as well to thenon-refractory materials previously mentioned. The gold compounds ofthis invention have the further advantage of being of fixed and readilyreproducible composition, since they are not derived from naturalproducts such as cyclic terpenes.

Further, while the ability to form a decorative film of precious metalat relatively low temperature is an outstanding property of the goldcompositions of this invention, the use of the gold compositions of thisinvention also is meritorious in attaining production of films ofmetallic gold which exhibit (1) a high degree of reflectivity to lightand particularly to infrared radiation, making them useful as reflectorsfor lamps, ovens, and the like; (2) electrical conductivity making themuseful in forming printed circuits and resistors and as bases forsoldering connections to non-conductive materials, for electroplatingand plating by dipping in molten metals and alloys; and (3) chemicalinertness, making them useful for protecting the underlying surface fromcorrosion, oxidation and the like.

In a preferred embodiment, the gold decorating compositions contain agold 'flux in addition to the lvehicle and the gold :aryl mercaptide.The choice of ingredients for the fiux determines the behavior of thegold film during and after firing, and is usually dictated by thecomposition of the article to be decorated and the use for which it isintended. The flux will usually contain small amounts of salts orresinates of rhodium or iridium to improve the continuity and brillianceof the gold film. Other ingredients such as salts and resinates ofbismuth, chromium, lead, cadmium, tin, copper, cobalt, antimony anduranium are employed to improve the adherence of the gold film and itsresistance to abrasion. The ingredients fuse to a low melting glass orglaze as a result of the firing. The conventional glazes can not be usedto promote adherence of the gold film to non-refractory materials suchas plastics and plastic laminates and the gold film on such material maybe protected, if desired, by a coating of lacquer or varnish or bylaminating a thin film of plastic to the surface. The lacquer may alsobe incorporated in the gold decorating compositions to provide anadherent film.

The vehicles which can be utilized in decorating compositions employingthe novel compounds of this invention include, in addition to simplesolvents, mixtures of essential oils, terpenes, resins and the like,carefully chosen to impart specific physical properties to thecomposition. The choice of vehicle controls the behavior of thecomposition befiore firing and is dictated by the method by which thecomposition is to be applied. The physical properties imparted to thecomposition by the vehicle chosen, such as oiliness, viscosity,evaporation rate, surface tension and tack, will vary for differentmethods of application, such as brushing, spraying, stippling, stamping,printing, both direct and offset, hot or cold screen printing,stenciling, decalcomania and the like. Typical vehicles include mixturesof two or more of the following ingredients: methyl ethyl ketone,cyclohexanone, ethyl acetate, *amyl acetate, cellosolve, butan-ol,nitrobenzene, toluene, xylene, petroleum ether, chloroform,carb-ontetrachlcride, various terpenes such as pinene, dipentene,dipentene oxide and the like, essential oils such as oils of lavender,rosemary, aniseed, Sassafras, Wintergreen, fennel, and turpentine,Assyrian asphalt, various rosins and balsams, and synthetic resins. 'Forspecial applications such as compositions for hot screening, specialvehicles such as waxes and thermoplastic resins may be used. Suchcomposition, when applied through a hot screen to an article maintainedat a relatively lower temperature, immediately set to a hard film andare more fully described in copending US. patent application Serial No.14,168, filed March 11, 1960, now US. Patent No. 3,092,504.

The gold aryl mercap-tides of this invention may be prepared by admixingan aryl mercaptan of the formula ArSH wherein Ar is an aryl radical andthe mercapto sulfur is attached directly to an aromatic ring of the arylradical with a gold salt, such as lauric bromide, auric iodide,potassium bromaur-ate or potassium iodoaurate. Auric chloride orpotassium chloraurate are preferred, however, since they are more stableand easy to prepare. Auric chloride is prepared by dissolving metallicgold in aqua regia and removing the nitric acid present byrepeatedevaporations with hydrochloric acid.

Removal of the excess hydrochloric acid is not necessary,

and the resulting solution, known as gold liquor, is suitable for use inpreparing gold aryl mercaptides. The gold liquor may be diluted withwater before use, or solvents such as ethyl acetate or methanol may beused. Preferably from three to four moles of mercaptan per mole of auricchloride are used, and higher ratios may be employed, but withoutsubstantial advantage. The reaction temperature may vary from about 0 C.to about 100 C. Usually, it is preferable to mix the mercaptan and goldsalt in a suitable solvent at a temperature in the range of about 10 toabout C. and to complete the reaction by heating to temperatures in therange of about to about C. The reaction is somewhat exothermic, and itis usually preferable to add one reactant to the other slowly or inincrements with cooling if required. The reaction product is obtained asan oil or an oily solid containing any excess mercaptan and largeamounts of disulfides formed in the reaction. The product is puritfiedby washing or leaching with methanol, or with mixtures of methanol withacetone, isopropanol or benzene. Some of the gold aryl mercaptides maybe further purified by crystallization from a suitable solvent such astoluene.

In this method of preparation, disulfides are formed according to thefollowing reaction, in which Ar has the ioregoing significance:

Thus, for every mole of me-rcapt-an combined as gold meroaptide, twomoles of mercaptan form the disulfide. This is disadvantageous,particularly when the more expensive mercaptans are used and withmercaptans torming the more soluble gold mercaptides, since substantialamounts of gold mercaptide are lost in separating the 'disulfide. Itwould, therefore, be advantageous to employ an aurous salt such asaurous chloride in the reaction in order to eliminate disul-fideformation. Aurous salts are notoriously difficult to make, however, andare of poor stability, and they tend to be contaminated with greater orlesser amounts of metallic gold. Some success has been claimed for theuse of aurous cyanide in various reactions, but the use thereof iscomplicated by the toxic nature of the hydrogen cyanide produced as aby-product.

Alkyl sulfides are known to react with auric halides to give alkylsulfide-aurous halide complexes according to the following equation inwhich R is a lower alkyl group, for instance methyl, ethyl, butyl oroctyl, and X is halogen, for instance chlorine, bromine or iodine:

In accordance with the present invention, it has been found that thealkyl sulfide-aurous halide complexes disclosed supra react with arylmercaptans to give gold aryl mercaptides according to the followingequation in which Ar, R and X have the foregoing significance:

The reaction proceeds smoothly at normal or room temperatures to givehigh yields of gold aryl mercaptides that are uncontaminated withdisulfides or metallic gold. Use of the methyl sulfide-aurous chloridecomplex or of the ethyl sulfide-aurous chloride complex is preferred,since auric chloride and methyl and ethyl sulfides are readily availableas starting materials and the sulfoxides and excess sulfides are readilyremoved from the product. In forming the alkyl sulfide-aurous halidecomplex, reaction temperatures between about 0 C. and about 40 C.,preferably between about 15 C. and about 25 C. are employed. Thereaction is effected by preferably mixing the alkly sulfide and goldhalide in an aqueous medium at the temperatures stated and, withoutisolating the reaction product, adding the aryl rnercaptan to thereaction mixture. The lower alkyl sulfide-aurous halide complexes tendto decompose upon exposure to air and upon attempted isolation orpurification, with the formation of metallic gold. This decomposition isavoided by using excess lower alkyl sulfide and by not isolating thelower alkyl sulfide-aurous halide complex. An excess of about onemole issufiicient to prevent decomposition, and it is preferred to use a totalof about 3 moles of lower alkyl sulfide per mole of auric halide. Higherratios may be used, but without substantial advantage. Temperatures muchabove in excess of 40 C. should be avoided due to the volatility of thelower alkyl sulfides and the instability of the complex. Temperaturesmuch below 0 C. should also be avoided due to the tendency of theaqueous reaction mixture to freeze, although somewhat lower temperaturesmay be used with solvents such as methanol. The reaction between thelower alkyl sulfide and the auric halide is somewhat exothermic, andcooling of the reaction mixture usually will be required. The reactionof the complex with the aryl mercaptan is only very mild-1y exothermic,and little cooling is required for this reaction. Other solvents such asmethanol may be used, but it is apparent from the above equations thatat least one mole of water is required for the reaction. When the goldsalt is in the form of gold liquor, sufiicient water usually will beavailable, but when anhydrous gold salts are used in solvents other thanwater, at least one mole of water per mole of gold salt should bepresent in the reaction mixture. The gold aryl mercaptides may berecovered from the reaction mixture by filtration or in the case of themore soluble gold aryl mercaptides by extraction with a suitable solventsuch as chloroform or toluene, and they may be purified, if desired, bywashing with water and with methanol and in some cases bycrystallization from a suitable solvent such as toluene or ethylacetate.

Although the aryl mercaptides of this invention are aurous mercaptides,they are referred to herein simply as gold mercaptides, since auricmercaptides are not known and the same aurous mercaptide is obtainedfrom auric salts and from aurous salts. Pure aryl mercaptans are notessential to the practice of this invention, and commercial grades aresuitable. Mixtures of aryl mercaptans may also be employed for reactionwith the organic sulfide-aurous halide complex to give mixtures of goldaryl mercaptides that are suitable for use in gold decoratingcompositions.

As previously pointed out, the gold compounds previously used indecorating compositions required relatively high temperatures to form ametallic film, limiting their application to the decoration ofrelatively refractory materials such as glass, ceramics, metals, quartz,carbon, mica and other materials that were not damaged by the hightemperatures required. An outstanding advantage of the gold arylmercaptide-containing decorating compositions of this invention is therelatively low temperature required to form a metallic film therefrom,extending their application to a wide range of plastics, plasticlaminates, wood, paper, textiles, leather and the like that would bedamaged and/or destroyed by high temperatures. A roughly quantitativeestimate of the firing temperatures required was made by brushingsolutions or suspensions in toluene, adjusted to a gold content of percent, onto glass slides. After evaporation of solvent, the slides wereheated for one hour in a precisely controlled mechanical convectionoven, and the films obtained were tested for electrical conductivity.The tests were repeated at temperature intervals of 5 C. to determinewithin 5 C. the minimum temperature required to pro duce conductivityshowing the formation of a continuous film of metallic gold on theslide. It will be recognized that firing would ordinarily be conductedat a higher temperature or for a longer period of time or both in orderto obtain maximum conductivity and brilliance of the film. Nevertheless,the minimum firing temperatures obtained in this manner give areproducible index of the relative temperatures required for practicaldecorating compositions. The results of these tests, listed in Table I,show that the compounds of the present invention fire g to metallicfilms at temperatures below those required for the gold sulforesinatesof the prior art.

TABLE I.MINIUUM TEMPERATURES REQUIRED TO OBTAIN A CONDUCTIVE FILM IN ONEHOUR Example Compound Tgnp,

Prior art Gold sulforesinate 270 Gold phenyl mercaptide 115 Goldo-rnethylphenyl mercaptide 215 Gold m-methylphenyl mercaptide. 130

Gold p-mothylphenyl mercaptide 135 Gold mixed methylphenyl mercaptidesGold p-tert.-butylphenyl mercaptide 230 Gold p-nonylphenyl mercaptide210 Ggll o-methyLp-tert.-butylphenyl mercap- Gold .Z-naphthyl mercaptide250 Gold p-ohlorophenyl mereaptido.

Gold pentachlorophenyl mereaptide 230 Gold o-earboxy-phenyl mercaptrde.225

Gold o-aminophenyl mereaptlde 255 Gold mixed dlrnethylphenyl mer0aptid2s215 The ability to form a metallic film at relatively low temperaturesis a distinct advantage even in applications on relatively refractorymaterials where it may be desirable to heat the material to the point ofincipient softening, which may vary from about 500 C. for a soft glassto about 800 C. for a ceramic glaze and even higher for refractorymaterials such as quartz to improve the adherence of the metallic film.The initial formation of the metallic film should take place in anoxidizing atmosphere in order to promptly and completely remove organicmatter from the film. This oxidizing atmosphere is usually provided bygood ventilation of the oven or kiln in which the metallic film isproduced, and such ventilation becomes increasingly difficult and costlywith increases in temperature, since heat is lost to the air introducedby ventilation. Once the metallic film has been developed, furtherheating may be accomplished without good ventilation and con sequentheat loss.

Among the gold decorating compositions which can be prepared employingthe novel compounds of this invention, the preferred compositions arethe liquid bright golds, which give specular bright films on firing.Generally speaking, the ingredients of the liquid bright golds are allsoluble in the vehicles employed, giving clear solutions, or becomesoluble in the vehicles in the process of firing. Another class of golddecorating com positions are the burnish gold decorating compositionssuch as are described, for example, by Chemnitius, J. Prakt. Chem. 117,245 (1927), by Ballard in U.S. Patent No. 2,383,704, and by Candna inBritish Patent No. 731,906. Generally speaking, such compositions contain insoluble ingredients such as, for example, gold powder, mercuricoxide, bismuth subnitr'ate and lead borate. They are employed as pastesor suspensions rather than as solutions and fire to gold films that aredull and matte in appearance. On burnishing, the films so obtained takeon the soft golden luster characteristic of burnished gold. The additionof the gold aryl mercaptides of this invention to such compositionsgives films that are brighter and require less burnishing than thoseobtained from the conventional burnish golds. As may be seen from theexamples that follow, gold aryl mercaptides may be employed withadvantage as the sole gold compounds in burnish gold decoratingcompositions.

Another class of gold decorating compositions is the gold lusters. Theselusters resemble liquid bright gold in composition, but containrelatively less gold and more gold flux. Instead of firing to aconductive film of bright gold, the gold luster compositions givenon-conductive films of various colors, depending upon the amount ofgold present and the nature of the gold flux, having a characteristicgolden sheen or luster. The colors produced are believed to result fromthe presence in the film of colloidal metallic gold in various particlesizes. The gold aryl mercaptides of this invention are suitableingredients for such luster compositions.

The gold aryl mercaptides of this invention are also suitable for use indecorating compositions containing other precious metals such asplatinum, palladium and silver that serve to modify the color,appearance, re-

flectivity and electrical conductivity of the metallic film formed onfiring. Platinum and palladium in such compositions give films rangingfrom reddish gold to silver to grey to black with increasing amounts ofplatinum or palladium. Silver compounds such as silver resinate givefilms of a lemon yellow color and with increasing amounts of silver of agreenish yellow color. Platinum and palladium resinates andsulforesinates such as those described by Chemnitius, Sprechsaal 60, 226(1927), and by Ernst in U.S. Patent No. 1,954,353 may be employed insuch compositions. Preferably, however, lower firing platinum andpalladium compounds such as those described in US. Patent No. 3,022,177and in my copending US. patent application 60,575, filed October 5,1960, are employed to take full advantage of the low firingcharacteristics of the gold aryl mercaptides of the invention.

The gold content of gold decorating compositions varies with the methodof application and intended use. Generally speaking, gold lu-sterscontain about 0.13 percent gold, liquid bright golds for sprayingcontain about 2-10 percent gold, liquid bright golds for brushingcontain about 5-15 percent gold, gold compositions for screening orstamping contain about 8-25 percent gold, and burnish golds may containabout 12-40 percent or more of gold, the percentages being by weight.

Firing temperatures employed range between about 150 and 1350 C.,preferably between about 200 and 800 C. Of course, the particular firingtemperature will depend on the substrate being decorated and will beconsiderably lower when decorating thermoplastic materials than whendecorating ceramics or ferrous metals such as stainless steel. It isusually advantageous to fire to the incipient softening point of thesubstrate. Temperatures of between 150 and 300 C. are advantageous forfiring the applied decorating composition on thermoplastic articles, andtemperatures between about 350 and 750 C. are advantageous for firingthe applied decorating material on glass. Firing temperatures betweenabout 450 and 700 C. are advantageously used for firing the decoratingmaterial on stainless steel, and firing temperatures between about 350and 900 C. are advantageously used when firing the decorating materialon porcelain and glazed earthenware. For some special applications suchas decorating and ceraming glassceramics in a single firing operation,temperatures as high as 1350 C. are required. Such high temperatures mayrequire special fluxes such as resinates of tantalum and niobium asdescribed in copending US. patent ap' plication No. 99,046, filed March29, 1961. In every case, the firing is carried out for a time sutficientto decompose the gold aryl mercaptides and volatilize the decompositionproducts.

In the specific examples that follow, test pieces coated with decoratingcompositions containing the novel compounds of the invention were firedunder various conditions. Where kiln firing is specified, it is to beunderstood that the pieces were placed in a kiln which Was heated to aspecified temperature, held at about this temperature for about minutesand cooled, the total operation requiring an hour or more. Where lehrfiring is specified, it is to be understood that the pieces were passedthrough a continuous lehr having a specified peak temperature, passagethrough the lehr requiring from one and one-fourth to one and one-halfhours. Where infrared firing is specified, the pieces were placed underan infra-red heat source giving a temperature of the order of 250 C. fora specified period of time. It is to be amples following were obtainedin capillary tubes heated at the rate of about 5 C. per minute.

The invention will be further illustrated by reference to the followingexamples:

EXAMPLE I Preparation 0 gold aryl mercaptides from aurous chloride-ethylsulfide In a typical preparation, 0.2 mole of gold in the form of goldliquor was added to a mixture of 0.6 mole ethyl sulfide and ml. waterduring 15 minutes with stirring and cooling to maintain the temperaturebetween 15 and 20 C. After stirring for 15 minutes longer to insurecompletion of the reaction, the product was a colorless upper aqueouslayer and a colorless to pale yellow lower layer consisting principallyof aurous chloride-ethyl sul fide complex and ethyl sulfide. Then 0.22mole of an aryl mercaptan was added with stirring over a period of timeranging from 10 minutes to 2 hours, maintaining the temperature of thereaction mixture at 20 C. or lower, and the mixture was stirred at aboutroom temperature for one-half to 2 hours longer to insure completion ofthe reaction. Solid aryl mercaptans were dissolved in methanol orchloroform before addition. The gold aryl mercaptide, which precipitatedas a granular solid or paste, was allowed to settle, and the aqueouslayer was removed by decantation or by siphoning. The residual layer waswashed by stirring with several 250 ml. portions of water, removing theaqueous layer after each wash. The residual layer was then washed in thesame manner with methanol and filtered. The precipitate was washed onthe filter with methanol and dried at room temperature. In some cases,particularly after the addition of methanol, the precipitate was tooflocculent to be washed by decantation and was washed only on thefilter. The gold aryl mercaptides listed below were prepared in theabove manner. Yields were almost quantitative.

A. Gold plzenyl mercaptide, prepared from benzenethiol, was obtained asa pale yellow solid containing 63.5 percent gold that decomposed withoutmelting ca. C.

B. Bold o-methylphenyl mercaptide, prepared from o-methylbenzenethiol,was obtained as a very pale yellow solid containing 61.5 percent goldthat melted with decomposition ca. 177 C.

C. Gold m-methylphenyl mercaptide, prepared from m-methylbenzenethiol,was obtained as a yellow solid containing 60.7 percent gold thatdecomposed without melting ca. C.

D. Gold p-methylphenyl mercaptz'ae, prepared from p-methylbenzenethiol,was obtained as a very pale yellow solid containing 61.5 percent goldthat decomposed without melting ca. 163 C.

E. Gold mixed met/zylphenyl mercaptides, prepared from a commercialmixture of methylbenzenethiols containing about 35 percento-methylbenzenethiol, 50 percent m-methylbenzenethiol and 15 percentp-methylbenzenethiol, was obtained as a yellow solid containing 61.4percent gold that decomposed without melting ca. 106 C.

F. Gold p-tert.-butylphenyl mercaptide, prepared fromp-tert.-butylbenzenethiol, was obtained as a yellow solid containing52.8 percent gold that darkened above 235 C. and melted withdecomposition about 265 C.

G. Gold p-nonylphenyl mercaptide was prepared from p-nonylbenzenethiol.After washing with water and methanol, it was obtained as an oil thatslowly solidified. This was dissolved in 50 ml. chloroform, and thesolution was added dropwise with good agitation to 1.2 liters of 9methanol, giving a yellow powder that was removed by filtration anddried. It contained 43.2 percent gold, softened ca. 118 C. and meltedindefinitely between 180 and 195 C.

H. Gold -methyl-p-tert.-butylphenyl mercaptide, prepared fromo-methyl-p-tert.-butylbenzenethiol, was obtained as a pale yellow solidcontaining 50.2 percent gold that melted at 251 C.

I. Gold Z-naphthyl mercaptide, prepared from Z-naphthalenethiol, wasobtained as a yellow solid containing 53.2 percent gold that decomposedwithout melting ca. 144 C.

J. Gold. p-chlorophenyl mercaptia'e, prepared from p-chlorobenzenethiol,was obtained as a yellow solid containing 57.5 percent gold that meltedwith decomposition ca. 172 C.

K. Gold pentachlorophenyl mercaptide, prepared frompentachlorobenzenethiol and washed well with benzene after washing withwater and methanol, was obtained as an off-white solid containing 40.6percent gold that melted with decomposition ca. 230 C.

L. Gold o-carboxy-phenyl mercaptide, prepared from o-mercaptobenzoicacid and washed with ethyl acetate after washing with water andmethanol, was obtained as a dark yellow solid containing 56.3 percentgold that decomposed without melting ca. 154 C.

M. Gold o-aminophenyl mercaptide was prepared from o-aminobenzenethiol.Before adding the mercaptan, the aurous chloride-ethyl sulfide complexwas separated from the aqueous layer and was washed with two 50 ml.portions of water to remove the acid present, and a solution of 0.5 molesodium acetate in 90 ml. water was added to bufier the hydrochloric acidsubsequently formed by reaction with the mercaptan. The product was adark yellow solid containing 59.0 percent gold that decomposed withoutmelting ca. 193 C.

EXAMPLE 2 Preparation of a gold aryl mercaptide from aurouschloride-methyl sulfide To a solution of 56.5 g. gold liquor containing34.9 percent gold (0.1 mole) in 500 ml. water was added 18.6 g. methylsulfide (0.3 mole) during 20 minutes wit-h stirring and cooling tomaintain the temperature below 5 C. Aurous chloride-methyl sulfidecomplex precipitated as a tan crystalline solid. The reaction mixturewas diluted with 80 ml. chloroform, and a solution of 18.3 g.p-tert.-butylbenzenethiol (0.11 mole) in ml. chloroform was added duringminutes with stirring and cooling to maintain the temperature between 5and 12 C. After stirring for 40 minutes longer while warming to roomtemperature, the reaction was complete as shown by complete solution ofthe solids present. The supernatant aqueous layer was removed bydecantation, and the residual chloroform layer was washed with three 250ml. portions of water, decanting the water after each wash. Remainingwater was removed in a separatory funnel, and the clear yellowchloroform solution was added dropwise with good agitation to one literof methanol during 40 minutes. The mixture was stirred for 30 minuteslonger and filtered. The precipitate, washed on the filter with 250 ml.methanol and dried, was 36.1 g. gold p-tert.-butylphenyl mercaptide as ayellow solid containing 54.3 percent gold that melted indefinitelybetween 205 and 215 C.

EXAMPLE 3 Preparation of a gold aryl mercaptide from auric chloride Asolution of 112.5 g. gold liquor containing percent gold (0.2 mole) in100 ml. ethyl acetate was added with stirring during /2 hour to 122.8 g.mixed dirnethyl- Ingredient:

benzenethiols (0.8 mole), a com'merical mixture of thioxylenols of aboutpercent purity. The temperature increased from 22 to 50 C. during theaddition, and there was opious evolution of hydrogen chloride. Afteradding 25 ml. more ethyl acetate and stirring for A2 hour longer, thetemperature had fallen to 30 C. The product was stirred well with 150ml. acetone, allowed to settle, and the supernatant solvent layer wasremoved by siphoning. The residue was stirred well with 200 ml. acetoneand filtered, and the precipitate was washed on the filter with 250 ml.acetone and air dried. The product was stirred well with 200 ml.benezene and was allowed to stand three days and filtered. Theprecipitate, washed on the filter with 200 ml. benezene and dried, was67.8 g. mixed gold dimethylplzenyl mercaptides as a pale yellow solidcontaining 58.1 percent gold that darkended ca. 205 C. and melted withdecomposition ut 230 C.

EXAMPLE 4 Decorating compositions containing gold p-tert.-butylphenylmercaptide A. BRIGHT GOLD DECORATING COMPOSITION FOR BRUSHING A fluxedgold concentrate was prepared by mixing the following ingredients:

Parts by weight Gold p-tert.-'butylphenyl mercaptide dissolved intoluene (30 percent Au) Rhodium resinate dissolved in a mixture ofessential oils and hydrocarbons (1 percent Rh) 15 Bismuth resinatedissolved in a mixture of essential oils (4.5 percent Bi) 10 Chromiumresinate dissolved in a mixture of cyclohexanone and oil of turpentine(2.05 percent Cr) 3 Oil of rosemary 22 Total A clear solution containing20 percent gold was obtained.

A bright gold decorating composition for brushing was prepared by mixingthe following ingredients:

Parts by Ingredient: weight Fluxed gold concentrate 300 Sulfurizedbalsam 168 Cyclohexanone 52 Oil of rosemary 51 Nitrobenzene 24 Oilsoluble red dye 5 Total 600 The clear, red solution thus obtainedcontained 10 percent gold and was applied 'by brushing to a variety ofarticles, which were fired under conditions suitable for the individualarticle. In every case, adherent, conductive, metallic golden films wereobtained on the articles, the appearance varying with the nature of thearticle as noted below.

Article Firing conditions Appearance A fiberglass laminated plasticpanel Mica sheet Stainless steel panel, type 430, polished surfaceAluminum panel, polished surface Soda lime clear glass tumbler Whiteporcelain enamel on steel panel- A glass-ceramic known as PyroceramTempered soda lime opal glass dish Borosilicate opal glass dishBorosilicate clear glass tubing Clear fused quartz panel Hard porcelain(china) dish Glazed earthenware tile Infra-red minutes. Infra-redminutes. Infra-red minutes Do 480 C. kiln 5 minutes.

Bright.

Do. SemLbright. Matte.

l The stainless steel-panel was flash fired by inserting in a kiln at500 C. and removing after 2 minutes.

2 The aluminum panel was flash fired by inserting in a kiln at 550 C.and removing after 3 minutes.

B. BRIGHT GOLD DECORATING COMPOSITION FOR SCREENING OR MACHINE BANDING Abright gold decorating composition suitable for screening or machinebanding was prepared by mixing the following ingredients:

The resulting solution was heated in an open dish on a steam bath until64 parts by weight had evaporated, leaving 86 parts by weight of clear,viscous, dark red oil containing 14 percent gold. This was applied byscreening through a 283 mesh Nitex screen onto a soda lime clear glasspanel and by machine banding onto a soda lime clear glass tumbler andonto a glazed earthenware dish, and these articles were lehr fired to600 C. In each case, bright, specular golden films were obtained.

C. BRIGHT GOLD DECORATING COMPOSITION FOR \STAMPING A' bright golddecorating composition suitable for stamping was prepared by furtherheating 50 parts by weight of the composition of B above in an open dishon a steam bath until an additional 7 parts by weight had evaporated,leaving 43 parts by weight of clear, very viscous, dark red oilcontaining 16.2 percent gold. This was rolled thin on a glass plate witha brayer. A rubber stamp was inked from the glass plate, and the designof the stamp was applied to a soda lime clear glass panel. On kilnfiring to 600 C., the design appeared as a bright, specular golden film.

D. GREEN GOLD DECORATING COMPOSITION A green gold decorating compositionwas prepared by mixing the following ingredients:

Parts by Ingredients: weight The fluxed gold concentrate of A above 300Silver resinate dissolved in a mixture of essential oils (24 percent Ag)75 Sulfurized balsam 190 Oil of rosemary Oil soluble red dye 5 Total 600E. GOLD LUSTER DECORATING COMPOSITION A gold luster decoratingcompositon was prepared by mixing the following ingredients:

Parts by Ingredients: weight The fluxed gold concentrate of A above 10Bismuth resinate dissolved in a mixture of essential oils (4.5 percentBi) 37 Rosin dissolved in oil of turpentine (50 percent rosin)Chloroform 32 Oil soluble red dye 1 Total 200 The clear red solutionthus obtained contained 1 perclear glass tumbler and to a glazed ceramictile. When the tumbler was kiln fired to 600 C., a bright purple,non-conductive film with a golden iridescence was obtained. When thetile was kiln fired to 740 C., a bright deep-purple, non-conductive filmwith a golden iridescence was obtained.

F. MATTE GOLD DECORATING COMPOSITION A matte gold decorating compositionwas obtained by mixing the following ingredients:

was applied by brushing to a soda lime clear glass tumbler, which waskiln fired to 600 C., and to a glazed earthenware tile, which was kilnfired to 740 C. In each case a matte golden film was obtained.

G. BRIGHT PLATINUM DECORATING COMPOSITION A gold concentrate containing20 percent gold was prepared by mixing the following ingredients to givea clear solution:

Parts by Ingredients weight Gold p-tert.-butylphenyl mercaptidedissolved in toluene (30 percent Au) 1500 Rhodium resinate dissolved ina mixture of essential oils and hydrocarbons (1 percent Rh) 225Sulfurized balsam 250 Oil of rosemary 275 Total 2250 A flux concentratewas prepared by mixing the following ingredients to give a clearsolution:

Parts by Ingredients: weight Bismuth resinate dissolved in a mixture ofessential oils (4.5 percent Bi) 20 Chromium resinate dissolved in amixture of cyclohexanone and oil of turpentine (2.05 percent Cr)Sulfurized balsam 187 Cyclohexanone 53 Oil of rosemary 50 Oil solublered dye 5 Total 320 A bright platinum decorating composition wasprepared by mixing the following ingredients:

Parts by Ingredients weight The gold concentrate above 18 Platinumresinate dissolved in a mixture of essential oils (12 percent Pt)Rhodium resinate dissolved in a mixture of essential oils andhydrocarbons (1 percent Rh) 12 The flux concentrate above 30 Total 120The clear, dark red solution thus obtained contained 3 percent gold and6 percent platinum and was applied by brushing to a soda lime clearglass tumbler, which was kiln fired to 600 C., and to a glazed ceramictile, which was kiln fired to 740 C. In each case bright, specularsilvery films were obtained that were excellent conductors ofelectricity and were readily solderable.

Another bright platinum decorating composition was prepared by mixingthe following ingredients:

Parts by Ingredients weight The gold concentrate above 18Chloroplatinous n-octylrnercaptide-ethyl sulfide complex, Example XVIIIof US. Patent No. 3,022,177, dissolved in toluene (30 percent Pt) 21Rhodium resinate dissolved in a mixture of essential oils andhydrocarbons (1 percent Rh) 12 The flux concentrate above 64 Oil ofrosemary 5 Total 120 The clear, red solution thus obtained contained 3percent gold and 5.25 percent platinum and was applied by brushing to asoda lime clear glass tumbler and to a glazed ceramic tile. The tumblerand tile were fired as described above, giving films substantiallyidentical to those obtained from the above composition containingplatinum resinate.

H. BRIGHT PALLADIUM DECORATING COMPOSITION A bright palladium decoratingcomposition was prepared by mixing the following ingredients:

Parts by Ingredients: weight The gold concentrate of G above 54 IPalladium resinate dissolved in a mixture of essential oils andhydrocarbons (9 percent Pd) 20 The flux concentrate of G above 46 Total120 The clear, dark red solution thus obtained contained 9 percent goldand 1.5 percent palladium. It was applied by brushing to a soda limeclear glass tumbler, which was kiln fired to 600 C., and to a glazedceramic tile, which was kiln fired to 740 C. In each case bright,specular silvery films were obtained that were excellent conductors ofelectricity and were readily solderable.

Another bright palladium decorating composition was prepared by mixingthe following ingredients:

Parts by Ingredients: weight The gold concentrate of G above 13Dichlorobisdi-n-butylsulfidepalladium (II) dissolved in toluene, ExampleI of U8. patent application Serial No. 60,575, filed Oct. 5, 1960percent Pd) 2 The flux concentrate of Example 5 16 Total 31 The turbidred solution thus obtained contained 8.4 percent gold and 1.3 percentpalladium and was applied by brushing to a soda lime clear glass tumblerand to a glazed earthenware tile. The tumbler and tile were fired asdescribed above, giving films substantially identical to those obtainedfrom the above composition containing palladium resinate.

I. BURNISH GOLD DECORATING COMPOSITION A burnish gold decoratingcomposition was prepared by mixing the following ingredients:

The resulting paste containing 18.3 per-cent gold was applied bybrushing to a glazed ceramic tile, which was kiln fired to 740 C. Amatte golden film was obtained that gave a rich, lustrous golden film onbeing burnished by rubbing with wet burnishing sand.

J. THERMOPLASTIC GOLD DECORATING COMPOSITION A thermoplastic golddecorating composition suitable for hot screening was prepared by mixingthe following ingredients:

Parts by Ingredients: weight Gold p-tert.-butylphenyl mercaptidedissolved in toluene (17.8 percent Au) v 45 Rhodium resinate dissolvedin a mixture of essential oils and hydrocarbons (1 percent Rh) 4 Bismuthresinate dissolved in a mixture of essential oils (4.5 percent Bi) 3Chromium resinate dissolved in a mixture of cyclohexanone and oil ofturpentine (2.05 percent Cr) 1 Sulfurized balsam Hydrogenated rosin(Staybelite Resin) 10 Stearic acid =Finely divided melamine powder 6Nitrobenzene 25 Total 149 The mixture was held in an open dish withoccasional stirring on a steam. bath under an infra-red lamp until 74parts by weight had evaporated. The residue was 75 parts by weight of aviscous oil containing 10.7 percent gold that set to a hard solid oncooling to room temperature. This was applied to a soda lime clear glasstumbler by screening through a 325 mesh stainless steel screenmaintained at about 85 C. The applied film immediately set to a hardtack-free state and gave a bright gold film on kiln firing to 600 C.

K. DUsTING GOLD DECORATING COMPOSITION A dusting gold decoratingcomposition was prepared by grinding together a mixture of the followingingredients to give a fine yellow powder containing 15.2, percent gold.

Parts by Ingredients; weight Gold p-tert.-butylphenyl mercaptide (53.3percent Au) 20 Mercuric oxide 46 Lead borate 3 Bismuth subnitrate 1Total 70 A stamping medium was prepared by heating a mixture of 20 partsby weight sulfurized balsam and 2 parts by weight of a solution ofrhodium resinate in a mixture of essential oils and hydrocarbons (1percent Rh) on a steam bath until 20 parts by weight remained. Theviscous tacky medium thus obtained was applied in the form of adecorative design by stamping on a glazed earthenware tile. The surfaceof the tile'was dusted with the above dusting composition, and excessdust not adhering to the design was removed by brushing. On kiln firingto 740 C., a matte, golden film was obtained.

EXAMPLE 5 Decorating composition containing gold m-methylphenylmercaptide A flux concentrate was prepared by mixing the followingingredients:

Parts by Ingredients: weight Rhodium resinate dissolved in a'mixture ofessential oils and hydrocarbons (1 percent Rh) 6 Bismuth resinatedissolved in a mixture of essential oils (4.5 percent Bi) 4 Chromiumresinate dissolved in a mixture of cyclohexanone and oil of turpentine(2.05 percent Cr) 1 Sulfurized balsam 3 Cyclohexanone 11 Total 60 A golddecorating composition was prepared by mixing the following ingredientson a roll mill:

Parts by Ingredients: weight H Gold m-methylphenyl mercaptide (60.7percent Flux concentrate 30 Rosin dissolved in oil of turpentine (50percent rosin) 3 Total 50 I The resulting paste containing 20.6 percentgold was thinned to brushing consistency with oil of turpentine andapplied by brushing to a glazed ceramic tile, which was kiln fired to740 C. A'matte; dark golden film was obtained that gave a soft, lustrousgolden film on burnishmg.

16 EXAMPLE 6 Decorating composition containing gold pentachlorophenylmercaptide A gold decorating composition was prepared by mixing thefollowing ingredients on a roll mill:

Parts by Ingredients: weight Gold pentachlorophenyl mercaptide (40.6percent The flux concentrate of Example 5 30 Rosin dissolved in oil ofturpentine (50 percent rosin) 3 Total 48 Parts by Ingredients: weightGold o-aminophenyl mercaptide (59.0 percent The flux concentrate ofExample 5 30 Rosin dissolved in oil of turpentine (50 percent rosin) 3Total 48 The resulting paste containing 18.4 percent gold was thinned tobrushing consistency with oil of turpentine and applied by brushing to aglazed ceramic tile, which was kiln fired to 740 C. The resulting mattegold film gave a rich, lustrous golden film on burnishing.

EXAMPLE 8 Decorating composition containing gold o-carboxy-phcnylmercaptid A gold decorating composition was prepared by mixing thefollowing ingredients on a roll mill:

Parts by Ingredients: weight Gold o-carboxy-phenyl mercaptide (56.3percent The flux concentrate of Example 5 30 Rosin dissolved in oil ofturpentine (50 percent rosin) Total 50 The resulting paste containing16.9 percent gold was thinned to brushing consistency with oil ofturpentine and brushed on a glazed ceramic tile, which was kiln fired to740 C. A matte gold film was obtained that gave a semi-bright goldenfilm on burnishing.

EXAMPLE 9 Decorating composition containing gold p-chlorophenylmercaptide A gold decorating composition was prepared by mixing thefollowing ingredients on a roll mill:

Parts by Ingredients: weight Gold p-chlorophenyl mercaptide (57.5percent The flux concentrate of Example 5 30 Rosin dissolved in oil ofturpentine (50 percent rosin) Total 50 The resulting paste containing17.3 percent gold was thinned to brushing consistency with oil ofturpentine and brushed on a glazed ceramic tile, which was kiln fired to740 C. A matte, brown film was obtained that gave a semi-bright goldenfilm on burnishing.

EXAMPLE Decorating compositions containing gold mixed dimethylphenylmercaptides A gold decorating composition was prepared by mixing thefollowing ingredients on a roll mill:

Parts by Ingredients: weight Gold mixed dimethylphenyl mercaptides (58.1

percent Au) The flux concentrate of Example 5 3O Rosin dissolved in oilof turpentine (50 percent rosin) Total 50 The resulting paste containing17.4 percent gold was thinned to brushing consistency with oil ofturpentine and brushed on a glazed ceramic tile, which was kiln fired to740 C. A matte gold film was obtained that gave .a lustrous golden filmon burnishing.

Another gold decorating composition was prepared by mixing the followingingredients on a roll mill:

Parts by Ingredients: weight Gold mixed dimethylphenyl mercaptides (58.1percent Au) Rhodium resinate dissolved in a mixture of essential oilsand hydrocarbons (1 percent Rh) Lead borate 3 Bismuth subnitrate 1Sulfurized balsam 36 Cyclohexanone Oil of rosemary 4 Total 100 Theresulting paste containing 17.4 percent gold was thinned to brushingconsistency with oil of turpentine and brushed on a glazed ceramic tile,which was kiln fired to 740 C. A matte brown film was obtained that gavea lustrous semi-bright golden film on burnishing.

EXAMPLE 11 Decorating compositions containing gold mixed methoylphenylmercaptides A burnish gold decorating composition was prepared by mixingthe following ingredients on a roll mill:

Parts by Ingredients: weight Gold mixed methylphenyl mercaptides (61.4

per cent Au) 15 The flux concentrate of Example 5 30 Rosin dissolved inoil of turpentine percent rosin) Total 50 The resulting paste containing18.4 percent gold was thinned to brushing consistency with oil ofturpentine and brushed on a glazed ceramic tile, which was kiln fired to740 C. A matte brown film was obtained that gave a rich, lustrous goldenfilm on burnishing.

A semi-bright gold decorating composition was prepared by nulling thefollowing ingredients on a glass slab:

Parts by Ingredients Weight Gold mixed methylphenyl mercaptides (61.4

percent Au) 36 Gold resinate dissolved in a mixture of essential oils(24 percent Au) 32 The flux concentrate of Example 4-G Total 218 Theresulting paste was shaken well with 15 parts by weight of rhodiumresinate dissolved in a mixture of essential oils and hydrocarbons (1percent Rh) and 67 parts by weight of oil of rosemary to give 300 partsby weight of a fine suspension containing 9.9 percent gold. This wasapplied by brushing to a soda lime clear glass tumbler, which was kilnfired to 600 C., and to a glazed ceramic tile, which was kiln fired to740 C. In each case, semi-bright golden films were obtained.

EXAMPLE 12 Decorating composition containing gold o-methylphenylmercaptide A gold decorating composition was prepared by mixing thefollowing ingredients on a roll mill:

Parts by Ingredients weight Gold o-methylphenyl mercaptide (61.5 percentThe flux concentrate of Example 5 30 Rosin dissolved in oil ofturpentine (50 percent rosin) Total 50 The resulting paste containing18.5 percent gold was thinned to brushing consistency with oil ofturpentine and brushed on a glazed ceramic tile, which was kiln fired to740 C. A matte gold film was obtained that gave a semi-bright goldenfilm on burnishing.

EXAMPLE 13 Decorating composition containing gold p-methylphenylmercaptide A gold decorating composition was prepared by mixing thefollowing ingredients on a roll mill:

Parts by Ingredients weight Gold p-methylphenyl mercaptide (61.5 percentThe flux concentrate of Example 5 30 Rosin dissolved in oil ofturpentine (50 percent rosin) Total 50 Total 50 Ingredients:

The resulting paste containing 16 percent geld was -thinned to brushingconsistency with oil of turpentine and brushed on a glazed ceramic tile,which was kiln fired to 740 C. A matte brown film was obtained thatParts by Ingredients: weight Gold phenyl mercaptide (63.5 percent Au) 15The flux concentrate of Example 30 Rosin dissolved in oil of turpentine(50 percent rosin) 5 Total 50 tane (30 percent gold) 5 The fluxconcentrate of Example 5 30 Total 42 The resulting paste was shaken Wellwith 18 parts by Weight of oil of rosemary to give 60 parts by weight ofa fine suspension containing 9.9 percent gold. This was brushed on asoda lime clear glass tumbler, which was kiln fired to 600 C., and on aglazed ceramic tile, which was kiln fired to 740 C. In each case asemibright golden film was obtained.

Another semi-bright gold decorating composition was prepared by mullingthe following ingredients on a glass plate:

Parts by weight Gold phenyl mercaptide (63.5 percent Au) 46 Gold pinenemercaptide (53.8 percent Au) 56 The flux concentrate of Example 4-G 300Total 402 The resulting paste was shaken with 30 parts by weight of asolution of rhodium resinate in a mixture of essential oils andhydrocarbons (1 percent Rh) and 168 which was kiln fired to 600 C., andon a glazed ceramic tile, which was kiln fired to 740 C. In each case asemi-bright golden film was obtained.

EXAMPLE 16 Decorating composition containing gold p-nonylphenylmercaptide A bright gold decorating composition was prepared by mixingthe following ingredients:

Parts by Ingredients Weight Gold p-nonylphenyl mercaptide (43.2 percentThe flux concentrate of Example 5 200 Toluene 31 Total u 300 Theresulting clear red solution containing 10 percent gold was brushed on aglazed ceramic tile, which was kiln fired to 740 C. A bright, speculargolden film was obtained.

EXAMPLE 17 Decorating composition containing gold o-methyl-p-tert.-butylphenyl mercaptide A bright gold decorating composition was preparedby mixing 15 parts by weight of a solution of goldo-methyl-p-tert.-butylphenyl mercaptide in toluene (16.7 percent Au)with 15 parts by weight of the flux concentrate of Example 5 to give 30parts by weight of a turbid solution containing 8.4 percent gold. Thiswas brushed on a soda lime clear glass tumbler, which was kiln fired to600 C., and on a glazed ceramic tile, which was kiln fired to 740 C. Ineach case a bright, specular golden film was obtained.

It will be obvious to those skilled in the art that many modificationsmay be made within the scope of the present invention without departingfrom the spirit thereof, and the invention includes all suchmodifications.

What is claimed is:

1. A nuclear-substituted gold aryl mercaptide including at least onealkyl group containing from three to eighteen carbon atoms attacheddirectly to the aryl nucleus.

2. Gold p-tert.-butylphenyl mercaptide. 3. Gold0-methy1-p-tert.-butylphenyl mercaptide. 4. Gold p-nonylphenylmercaptide.

References Cited by the Examiner TOBIAS E. LEVOW, Primary Examiner. H.M. S. SNEED, Assistant Examiner.

1. A NUCLEAR-SUBSTITUTED GOLD ARYL MERCAPTIDE INCLUDING AT LEAST ONEALKYL GROUP CONSISTING FROM THREE TO EIGHTEEN CARBON ATOMS ATTACHEDDIRECTLY TO THE ARYL NUCLEUS.